Characterization of active compounds against strawberry anthracnose produced by Photorhabdus akhurstii
| Autor: | Jie-Siang Chiu, 邱倢緗 |
|---|---|
| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 Strawberries is an important crop and generates substantial economic values for farmers in Taiwan. Colletotrichum gloeosporioides (Cg) is one of the main pathogens in the cultivation of strawberry, which is also called strawberry anthracnose. This disease causes severe loss in strawberry production. Spraying the pesticides is a general practice to reduce the loss caused by anthracnose in the field. However, overuse of the chemical pesticides brings many problems such as the pollution in environments, emergence of drug-resistant strains, food safety risks and the health of the farmers. So, biological control is proposed as an alternative approach to replace chemical pesticides. In this study, the antagonistic assays showed that Bacillus amyloliquefaciens strain ASB111 and Photorhabdus akhurstii sp. nov. 0813-124 phase I (PL1) had anti-Cg ability. In addition, PL1 also had the ability against several other Colletotrichum spp. PL1 was chosen for further analyses to identify novel anti-Cg compounds and to elucidate the mechanisms for PL1 against Cg. PL1 grown in the iron limited medium (LP) at the first 24hr culture time had the highest inhibitory activity, and PL1 could not grow in potato dextrose broth (PDB). Interestingly, PL1 was induced to produce active compounds in PDB agar (PDA). Among different extraction methods, the cut-agar method and EA extraction had the best extraction efficiency. The active compounds of EA extracts were purified by high-performance-liquid-chromatography (HPLC) and identified by high resolution and high mass accuracy experiments (Mass spectrometry). By integrating MS spectra, MS fragments and structure prediction, the active compounds of PL1 were identified as glidobactin A (m/z 521), cepafungin I (m/z 535) and glidobactin C (m/z 549), all of which belong to the syrbactin family. Base on MS spectra, active compounds of syrbactin family could be highly extracted in the cut-agar extraction. The active compounds might be induced by the incubation on the PDA. In addition, PL phase II (PL2) did not have anti-Cg ability. According to the anti-SMASH analysis of whole genome sequencing, PL1 and PL2 had 22 biosynthetic gene clusters (BGCs). Among the clusters, region 8 showed 26% of genes were similar to glidobactin and region15 showed 15% of genes were similar to glidobactin. Thus, we hypothesize that the different antagonistic abilities of PL1 and PL2 might be caused by differential expression of genes in the syrbactin family biosynthetic pathway. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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